Internal combustion engines convert chemical energy in fuel into mechanical energy through a series of explosions within a combustion chamber of the engine. These explosions cause pistons of the engine to reciprocate within associated cylinders. Each piston is typically connected to a crankshaft by a connecting rod, such that movement of the piston results in rotation of the crankshaft. The cylinders can be arranged in two banks positioned at an angle to each other. Each bank usually includes a group of cylinders located on the same side of the crankshaft with their axes lying in a common plane passing through an axis of the crankshaft. Each piston is typically encircled by a plurality of piston rings, which are received by machined grooves defined in the outer surface of the piston and help to seal off the combustion chamber. A cylinder liner can be fitted in a cylindrical space in which the piston reciprocates to protect the cylinder from wear and degradation.
During engine operation, the cylinder liner forms a sliding surface for the piston and piston rings. Over time, the cylinder liner can experience wear from friction of the piston and piston rings and therefore degrade in performance. For example, the piston and/or the piston rings can scuff the liner by forming local microscopic welding to the cylinder liner. Cylinder liners fitted for uniflow two-stroke diesel engines can be particularly sensitive to wear induced by scuffing because hard particulates can be dragged along the cylinder liner after passing by intake ports in the cylinder wall. Scuffing can result in elevated friction and wear of the cylinder liner, which can reduce the durability, reliability, and efficiency of the engine.
Reducing cylinder liner wear is generally accomplished by ensuring that adequate lubrication exists between the piston and/or the piston rings and the cylinder liner. One attempt to provide lower friction and wear to cylinder liners is described in U.S. Pat. No. 7,104,240 to Vuk et al. (“Vuk”) that issued on Sep. 12, 2006. Vuk discloses a cylinder liner that includes a plurality of discrete oil retaining indentations in a predefined pattern on its surface. Vuk aims to improve lubrication by arranging the distribution density of the discrete oil retaining indentations to correspond to the greatest lubrication needs of the cylinder liner. In particular, the discrete oil retaining indentations are more densely positioned at the longitudinal ends of the cylinder liner and less densely positioned at the longitudinal middle of the cylinder liner.
Although the discrete oil retaining indentations of Vuk may help reduce cylinder liner friction and wear, it may be less than optimal. This is because the configuration disclosed in Vuk may result in excessive oil being retained on the upper section of the cylinder liner. Excessive oil left on the upper section of the cylinder liner may subsequently be carried to the combustion chamber by the piston rings. The excessive oil may be burned during the combustion process and subsequently injected into the atmosphere as undesirable particulate emissions via an exhaust manifold of the engine. The particulate emissions produced by the discrete oil retaining indentations of Vuk may not meet governmental emission standards.
The cylinder liner of the present disclosure solves one or more of the problems set forth above and/or other problems in the art.